Relations between subsurface damage depth and surface roughness using the Abbott Firestone curve

Subsurface damages (SSD), which are introduce during grinding process of optical components for high power lasers applications, act as initiator for laser damage and are responsible of the low lifetime of these components. The knowledge of the SSD depth is essential to remove the damaged layer of the optical component during the last finishing step of grinding. However, existing methods to measure the SSD depth are either destructives or costly and complicated. Thus these methods are hardly useable industrially. That is why many studies have been made on the relation between the SSD and the surface roughness of grinded glasses. These studies founded several relations between the SSD depth and the peak to valley roughness (Rt), but the observed relations between these two parameters change with the grinding mode used and with the surface roughness measurement methods. In our study, the relations between SSD and surface roughness are widely explored to find a better and easier way to assess the SSD depth. For that purpose other surface roughness parameters are measured, especially the one from Abbott Firestone curve. Several grinding modes are tested, from rough grinding to finishing, with loose or bound abrasives. Finally, the accuracy of the relations between SSD and surface roughness is also studied. The results show that the 100-Mr2 parameter from the Abbott Firestone curve is more accurate than Rt for an assessment of the SSD depth.